Increasing gracilis muscle interstitial potassium concentrations stimulate group III and IV afferents

K. J. Rybicki, T. G. Waldrop, Marc Kaufman

Research output: Contribution to journalArticle

98 Citations (Scopus)

Abstract

Static muscular contraction reflexly increases arterial blood pressure and heart rate. One possible mechanism evoking this reflex is that potassium accumulates in the interstitial space of a working muscle to stimulate group III and IV afferents whose activation in turn evokes a pressor response. The responses of group III and IV muscle afferents to increases in interstitial potassium concentrations within the range evoked by static contraction are unknown. Thus we injected potassium chloride into the gracilis artery of anesthetized dogs while we measured both gracilis muscle interstitial potassium concentrations with potassium-selective electrodes and the impulse activity of afferents in the gracilis nerve. We found that increasing interstitial potassium concentrations to levels similar to those seen during static contraction stimulated 14 of 16 group III and 29 of 31 group IV afferents. The responses of the afferents to potassium were concentration dependent. The typical response to potassium consisted of a burst of impulses, an effect that returned to control firing rates within 26 s, even though interstitial potassium concentrations remained elevated for several minutes. Although our results suggest that potassium may play a role in initiating the reflex cardiovascular responses to static muscular contraction, the accumulation of this ion does not appear to be solely responsible for maintaining the pressor response for the duration of the contraction.

Original languageEnglish (US)
Pages (from-to)936-941
Number of pages6
JournalJournal of Applied Physiology
Volume58
Issue number3
StatePublished - 1985

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Potassium
Muscle Contraction
Reflex
Gracilis Muscle
Muscles
Potassium Chloride
Arterial Pressure
Electrodes
Arteries
Heart Rate
Dogs
Ions

All Science Journal Classification (ASJC) codes

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

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Increasing gracilis muscle interstitial potassium concentrations stimulate group III and IV afferents. / Rybicki, K. J.; Waldrop, T. G.; Kaufman, Marc.

In: Journal of Applied Physiology, Vol. 58, No. 3, 1985, p. 936-941.

Research output: Contribution to journalArticle

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